Safety fastening for doors



March 1934- e. s. coMsTocK SAFETY FASTENING FOR DOORS Filed 001;. 10, 1931 Mung is? W k'afyui $175M Patented Mar. 27, 1934 PATENT OFFICE SAFETY FASTENING FOR DOORS George S. Comstock, Steelton, Pa., assignor to Bethlehem Steel Company, a corporation of Pennsylvania Application October 10, 1931, Serial No. 568,097

2 Claims.

My invention relates to a safety-fastening device for firebox doors, especially such doors of the ordinary swinging or hinged type designed for manual operation, wherein it is required, or

necessary, to provide a high degree of safety and assurance of the door functioning properly under ordinary operating conditions.

The need for such a safety-fastening device is particularly present in both stationary and locomotive boiler fireboxes, where in the event of a flue or arch tube bursting the released pressure tends to blow open an improperly latched firebox door with the ensuing result of endangering the lives of the boiler attendants and of causing possible damage to property, and where both of the latter would otherwise be averted.

Due to this need of a safety-fastening device for firebox doors, it is becoming increasingly compulsory, owing to state laws relating to factory safety requirements, to provide existing steam power plant equipment with doors having some approved type of safety-fastening device.

Such an approved type of firebox door safetyfastening is required to be simple, rugged, and

.25 strong in design. It must be adapted to be cheaply and readily applied to existing equipment, either of a single or adouble door type.

It must function efficiently and automatically under normal operating conditions. And to have widespread use it must be economical to manufacture.

It is the object of my invention to meet the requirements and conditions stated above by means of novel features which will be more fully understood from the following description and claims taken with the drawing in which:

' Fig. 1 is a front elevation of a typical installation of my invention applied to a boiler front having a firebox opening equipped with double doors. One door is removed for purposes of clarity;

Fig.2 is a side elevation of the installation shown in Fig. 1, and a part section of the keeperplate and furnace front taken along the line 2--2 of Fig. l. The door is shown closed with thesafety-fastening device in latched position;

Fig. 3 is a plan view in part section taken along the line 33 of Fig. 2, and with the firebox doors removed; and,

Fig. 4 is a side elevation in part section taken along the line 4-4 of Fig. 3, and with the safetyfastening device in unlatched position.

As illustrated in the accompanying drawing, I have shown a boiler front 10 provided with the firebox opening 11 and the hinge-pin lugs 12.

The firebox opening 11 is designed to have as a closure two firebox doors 13 (one only shown) hinged at their opposite ends by means' of the door hinge-pin lugs 14 and the hinge-pin 15 mounted in the hinge-pin lugs 12. The fire doors have the conventional type damper 16 which is rotatable upon the bolt 17 and is provided with the air ports 18.

The safety-fastening device comprises a keeper-plate 19 secured to the boiler front'lO by suitable fastening devices 20, and a latch mechanism 21 secured to each of the firebox doors 13 by suitable fastening devices 22 and 23. As fastening devices I prefer to use through-bolts and nuts on the firebox doors, and I purposely make the devices '23 larger than the devices 22 in order to properly proportion the loads thereon, since the devices 23 are subject to considerable tensile stresses not imposed upon the devices 22. This latter by reason of the latch action should the firebox door be suddenly subjected to pressure from within the firebox. For the same reason a reinforcing plate 24 is used on the inside of the firebox door 13 in connection with the fastening devices 23. Filler plates 25 and 26 are provided 30 between the latch mechanism 21 and the firebox door 13. The thickness of these filler plates 25 and 26 is adjusted to assure proper engagement of the latch mechanism 21 with the keeperplate 19.

The keeper-plate 19 may be of any suitable material but I prefer to make it of the design as shown wherein a steel plate 27 is welded to a bracket 28 made from a commercial structural steel angle bar. Apertures 29 in the keeper-plate 19 are provided with the substantially vertical engaging faces 30, the purpose for which will hereinafter be described.

The, latch mechanism 21 comprises a mounting bracket 31 carrying a shaft pin 32 mounted therein, a gravity latch 33, and a handle 34, both the latter being pivotally mounted about the shaft-pin 32. The bracket 31 may be of any suitable material or construction, however, I prefer to make it of the design shown wherein commercial steel plate is utilized to make the base plate 35, the outwardly extending sides 36 and 37, a stop-plate 38, and the reinforcing ribs 39 and 40; after which I weld these together to make the integral bracket 31. The pin 32 has its bearings in the outer ends of the sides 36 and 37, and is preferably made with an integral head 41, and is provided with suitable retaining means, suchas a washer 42 and a split-pin 43. The gravity latch 33 may be made of any suitable material or construction, but, I prefer to make it from commercial steel plate and to weld a hub-washer 44 thereon to increase its pivot-bearing area. An aperture, the purpose of which will hereinafter be described, is provided in the latch 33 having a tangentially disposed portion 45 closed by a stop face 46, and a radially disposed portion 4? closed by a stop-face 43. The latch 33 is provided with a stop-face 49. The center of gravity of the latch 33 in relation to its pivot point when in its assembled operating position is such that the latch is biased downwardly which action when otherwise unopposed'brings the stop-face 43 into engagement with the stop-face 50 of the stop-plate 38 on the bracket 31, thus positioning the latch 33 in relation to the bracket 31. The latch 33 is also provided with the substantially vertical latch engaging face 51, which when the latch is in its working assembled latched position is in engagement with and opposed to an engaging face 30 of the keeper-plate 19. The handle 34 may be made of any suitable material or con struction, but, I prefer to make it from commercial steel plate and to weld thereto; a pipe bearing 52 which acts also as a locating member between the bracket sides 36 and 37; a plate 52 which serves as a reinforcing member; and a retaining stud 53 having a cylindrical body 54 and a shouldered head 55. The handle 34 is provided with a stop-face 56, and a hand-hole aperture 57. The center of gravity of the handle 34 in relation to its pivot point when in its assembled operating position is such that the latch is biased downwardly, whi h action when otherwise unopposed brings the stop-face 56 into engagement with the stop-face 50 of the stop-plate 38 on the bracket 31, thus positioning the handle 34 in relation to the bracket 31.

In assembling the latch mechanism 21, the latch 33 is first assembled on the handle 34. The pivot bearing of the latch 33 is placed over the projecting end of the pipe bearing 52 of the handle 34 simultaneously with the entry of the shouldered head 55 of the stud 53 on the handle 34 through the radially disposed. portion 47 of the aperture in the latch 33. The completion of the assembly of the latch 33 on the handle 34 is then made by rotating the latch 33 in relation to the handle 34 until the stop-face 46 of the latch 33 engages the body 54 of the stud 53 on the handle 34. With the latch 33 and handle 34 thus assembled they are next placed in position between the plates 36 and 37 of the bracket 31, and secured thereto by means of the shaft-pin 32. When properly assembled in latched position as shown in Fig. 2 the stop-face 49 of the latch 33, and the stop-face 56 of the handle 34, are both in engagement with the stop-face 50 of the stop-plate 38 of the bracket 31; and, furthermore, the stop-face 46 of the latch 33 is in engagement with the body 54 of the stud 53 on the handle 34.

Assuming that the safety-fastening device is thus assembled in place, with the doors closed and latched as shown in Fig. 2, I will now describe the operation of my invention. When the fire man, or operator, desires to open the firebox door, he grasps the handle 34 through the aperture 57 and pulls rearwardly, which action first raises the latch 33 from engagement with the keeper-plate 19 to the position shown in Fig. 4 and then opens the firebox door. The rearward pull on the handle 34 tends to rotate the handle 34 about the shaft-pin 32, and, by reason of the aforementioned engagement of the stud 53 with the stop-face 46 this rotational movement is transmitted to the latch 33 thereby moving it to its unlatched position in which the stop-face 58' on the latch 33 is in engagement with the stop-face 59 of the stop-plate 33. When the fireman, or operator, desires to close the firebox door 13 he can grasp the handle 34 and thus push the door to its closed position, or he can push directly against the handle without graspit, or he can push directly against the door until closed, or he can slam the door to its closed position, and in any of these events the door will automatically latch in the closed position independently of the handle. It is readily seen from the herein aforementioned description that any pushing action against the handle 34 only tends to hold it more firmly in its normal latched position. It is just as readily seen that the latch 33 in this case (the latched position of the handle 34) is free to be moved from its latched position to its unlatched position by reason of the range of relative rotational movement allowed between the handle 34 and the latch 33 by the movement of the stud 53 of the handle 34 between the stopfaces 46 and 48 of the latch 33. The latch action therefore in closing the door 13 is: As the door 13 moves forward the sloping face 60 of the latch 33 comes into engagement with the sloping face 61 of the keeper-plate 19 and the latch 33 is raised thereby independently of the handle 34. As the closing action of the door 13 continues, the latch 33, still free as regards the handle 34, slides over the keeper-plate in an unlatched position until the door 13 comes into closed position contact with the boiler front 13, which position (as previously determined in assembly) is that in which the engaging face 51 of the latch 33 has cleared the engaging face as of the keeper-plate l9 and the latch 33 by reason of the force of gravity falls downward into its latched position. Furthermore, in the case of the firebox door being slammed to its closed position, the latching action of the latch is accelerated by reason of its inertia, which, concentrated in its center of gravity forward of and above the pivot point of the latch 33, thereby tends to add to the force of gravity in closing the latch 33 when the door is suddenly brought to a standstill in its closed position.

From the foregoing description it will be seen that I have devised a simple and novel safetyfastening device forflrebox doors and the like, which functions automatically to latch and unlatch under normal operation of the doors, and in addition has the desirable advantages hereinbefo-re enumerated in the statement of the invention.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore that only such limitations shall be place thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In combination with a furnace front having a firebox opening and a pivotally attached firebox door as a closure thereto, a safety-fastening mechanism comprising a keeper-plate adapted for attachment to the said furnace front below the said firebox opening and having a latch engaging surface, and a latch mechanism comprising a bracket adapted for attachment to the said firebox door and having a stop surface, a shaft mounted in the said bracket, a latch pivotally mounted on the said shaft and normally biased to a latched position against the said stop surface, and a handle pivotally mounted on the said shaft and normally biased against the said stop surface, the said latch having unlatching movement independent of the said handle when engaging the said keeper-plate and adapted for latched engagement with the said latch engaging surface, and the said handle being adapted for operative unlatching engagement with the said latch.

2. In combination with a furnace front having a firebox opening and a pivotally attached firebox door as a closure thereto, a safety-fastening mechanism comprising a keeper-plate adapted for attachment to the said furnace front below the said firebox opening and having a latch engaging surface, and a latch mechanism adapted for attachment to the said firebox door and for operable engagement with the said keeper-plate, the said latch mechanism comprising a bracket having a stop surface, a shaft mounted in the said bracket, a gravity latch pivotally mounted on the said shaft and normally engaging the said stop surface, and a gravity positioned handle pivotally mounted on the said shaft and normally engaging the said stop surface, the said latch being so engaged with the said handle as to move in unison with an unlatching movement of the handle and to have limited unlatching movement relative to the said handle when the said handle is in its normal latched position.

GEORGE S. COMSTOCK. 

